Communication system



Feb. 22, 1949. J. R. DESCH ETAL COMMUNICATION SYSTEM 9 Sheets-Sheet 1 Original Filed Sept. 16, 1942 INVENTORS JOSEPH R. DESCH ROBERT E. MUMMA 8 ERNEST L/ GULDEN THEIR ATTORNEY Feb. 22, 1949. J. R. DESCH EI'AL COMMUNICATION SYSTEM 9 SheetsP-Sheet 2 Original Filed Sept. 16, 1942 INVENTORS JOSGPH R. 0556' R0857?! E "m4 3 ERNEST y GULDEN All All

AAAA b THEIR ATTORNEY Feb. 22, 1949. J. R. DESCH ETAL COMMUNICATION SYSTEM 9 Shasta-Sheet 3 Original Filed Sept. 16, 1942 INVENTORS JOSEPH R. DESGH ROBERT 6'. M A 8 ERNEST V. GULDEN e 8 1M AAAA A II AAAA IIIF

THEIR ATTQRNEY Feb. 22, 1949. J. R. DESCH arm.

COMMUNICATION SYSTEM 9 Sheets-Sheet 4 Original Filed Sept. 16, 1942 INVENTORS JOSEPH R DESGH ROBERT E. MUMMA 8 ERNEST Y GULDE'N THEIR ATTORNEY Feb. 22, 1949. J. R. DESCH ETAL COMMUNICATION SYSTEM 9 Shets-Sheet 5 Original Filed Sept. 16, 1942 INVENTORS MEPH R DESCH ROBERT E. MUMMA 8 ERNEST l. GULDEN All 7' All.

THEIR ATTORNEY Feb. 22, 1949.

J. R. DESCH ET AL COMMUNICATION SYSTEM 9 Sheets-Sheet 6 Original Filed Sept. 16, 1942 FIG.6

lNVENTORS JOSEPH R. DESCH ROBERT E. MUMM4 8 ERNEST ll GULDEN THEIR ATTORNEY Feb. 22, 1949. .1. R. DESCH ETAL COMMUNICATION SYSTEM 9 Sheets-Sheet 7 Original Filed Sept. 16, 1942 INVENTORS JOSEPH R. DESCH ROBERT E. MUMMA ERNEST Y GULDEN eY W M wElFf ATTORNEY Feb. 22, 1949. J. R. DESCH ETAL COMMUNICATION SYSTEM 9 Sheets$heet 8 Original Filed. Sept. 16, 1942 FIG. 8

FIG. 9

A SPACE INVENTORS JOSEPH I? 055671 ROBERT E. MUMMA 8 ERNEST ll. GULDEN THEIR ATTORNEY Feb. 22. 1949. J. R. DESCH EI'AL 2,462,613

coummIcA'rIoN sYsTEm Original Filed Sept. 16, 1942 9 Sheets-Sheet e Summon JOSEPH R. DESCH ROBERT E. MUMMA 8 ERNEST V. GULDEN by 4M Thnir Gttomeg Patented Feb. 22, 1949 COMMUNICATION SYSTEM Joseph R. Desch, Ernest V. Gulden, and Robert E. Momma, Dayton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Original application September 10, 1942. Serial No. 458,546, now Patent No. 2,425,307, dated August 12, 1947. Divided and this application February 19, 1944, Serial No. 523,025

14 Claims. 1

This invention relates to communication systems and is directed particularly to a receiving apparatus for use in a system in which various symbols making up the data to be transmitted are transformed into bursts or trains of discrete rapidly recurring signals, the number of signals in each burst being dependent upon the symbol which it represents. The bursts representing the difierent symbols are sent one after another over a single communication channel, with suitable spacing between bursts, and a marking signal is provided for each burst to indicate the completion of the burst. The marking signal is used to control the receiving apparatus to govern the allocation and storage of the symbols therein. The signals by which the symbols may be represented may take various forms, as, for instance, interruption or modulation of a continuous carrier wave and/or discrete rapidly recurring impulses, or representations thereof.

This application is a division of the application for United States Letters Patent, Serial No. 458,546, which was filed by Joseph R. Desch. Ernest V. Gulden, and Robert E. Mumma on September 16, 1942, and which issued on August 12, 1947, as Patent No. 2,425,307.

The sending apparatus used in the system is provided with means for generating the spaced bursts of signals, and controls the number of signals in each burst according to the symbol being sent. The signals can be transmitted by any convenient means--for instance, over a wire or by radio-to the receiving and storing apparatus, where they are transformed back into single representations of the symbols and are stored.

The receiving apparatus contains a plurality of transforming and symbol-storing means, each consisting of a group of devices, which transforming and symbol-storing means may be selectively and successively rendered eflective under control of the marking signals to receive the symbol-representing signals and which devices of a group represent the symbols and are diflerentially operated according to the number of signals in a burst to transform the signals back into a single or direct representation of the symbol and to store this representation.

The receiving apparatus responds to the signals when they are received, and, since it is the number of signals and not their position in a tired cycle which is the controlling factor, there is no need to synchronize the operation of the sending and receiving apparatus either before or during a transmitting operation.

High-speed communication of data is obtained with applicants novel arrangement because the sending and receiving apparatus can generate and respond to the signals at a high frequency and because the signal bursts which are used to represent the various symbols require only the time necessary to produce the number of signals needed to represent the symbols and can follow one after the other in transmission without unnecessary loss of time between bursts.

Furthermore, there is no particular sequential relation between the various symbols and the number of signals which may be used to represent them, so that the number of signals which represent any symbol may be chosen arbitrarily. Because of this condition, the symbols used most frequently can be represented by the smaller number of signals, and this will also reduce the time required for transmitting data.

It is an object of the invention, therefore, to provide means for receiving dlii'erent numbers of discrete signals which represent symbols and transforming the signals into a representation of the symbols.

A further object of the invention is to provide a receiving means for receiving bursts of signals consisting of signals having one characteflstic and signals having a distinctive characteristic, and having discriminating means to distinguish between the signals having different characterun s and to control the receiving means according y.

A further object of the invention is to provide a means for receiving and transforming bursts of symbol-representing signals into direct representations of the various symbols, each of said bursts containing a number of similar discrete signals and a control signal, and said receiving means containing a plurality of transforming means for setting up direct representations of the various symbols according to the number of signals in a burst and a routing means controlled by the control signals to route the bursts to the diiferent transforming means.

with these and incidental objects in View, the invention includes certain novel features of construction and combinations of parts, the essential elements of which are set forth in appended claims and a preferred form or embodiment of which is hereinafter described with reference to the drawings which accompany and form a part of this specification.

In the drawings:

Figs. 1 to 5 inclusive show portions of the transforming and symbol-storing means in the receiving apparatus, which means consists of groups or banks of symbol-representing tubes which may be selectively set according to the symbols corresponding to the impulses sent by the sending apparatus.

Fig. 6 shows relay means for selectively directing or routing impulses to the various groups of transforming and symbol-storing means.

Fig. 7 shows a routing control device containing a plurality of sequentially operable tubes which are controlled by the marking signals to control the relay means which route the impulses representing various symbols into the proper groups or banks of transforming and symbolstoring means.

Fig. 8 shows means in the receiving apparatus for discriminating between symbol-representing impulses and marking impulses and controlling the receivin apparatus according to the significance of the impulses.

Fig. 9 is a. representation of five bursts which may be transmitted in succession and illustrates the general character of the trains of signals by which the symbols are transmitted.

Fig. 10 illustrates an alternate form of routing means.

GENERAL Dnsciur'nou The symbols which may be sent to and received by the novel receiving apparatus may represent any selected data such as the digits of a numerical notation, the letters of the alphabet, or any other arbitrary data which may be chosen.

The disclosed embodiment is shown with a capacity for automatically receiving and storing five symbols in succession and is arranged to receive and store the letters of the alphabet.

For the purpose of this disclosure, the signals whereby the symbols are represented will consist of discrete, rapidly recurring impulses, and these impulses will be transmitted from a sendin apparatus to the receiving apparatus over a wire. It is not intended to limit the invention to this particular form of signal and transmission medium, as the invention is'capable of being carried out by using other equivalent arrangements.

The sending apparatus which generates the signals or impulses is capable of being differentially controlled to provide five groups or bursts of impulses, each burst of which contains a number of small-amplitude impulses according to the symbol represented thereby, and also contains a large-amplitude marking impulse which follows the small-amplitude impulses. The bursts are sent out one after another with a space or time interval between successive bursts, and are impressed on the input terminals of the receiving apparatus. The impulses of a burst follow each other at a frequency of 50 kilocycles, and a. space or time interval of 100 microseconds occurs between bursts.

The novel receiving apparatus contains a discriminating means which receives the impulses and is capable of distinguishing between the small-amplitude and the large-amplitude impulses; a routing means; and a plurality of transforming and symbol-storing means consisting of groups or banks of gaseous electron tubes for transforming the bursts of impulses into single representations of the symbols and storing the symbols.

Each group or bank of transforming and sympol-storing tubes contains a tube representing each symbol, a tube corresponding to the marking impulse, and a presetting tube. The marking impulse and symbol-representing tubes of each bank are connected to be tired one after another in response to the impulses sent out by the sending apparatus, the order of firing beginning with the marking impulse tube, then the space symbol tube, and next the tubes for the symbols A to Z. As each tube in the bank is fired, it extlngulshes any previously conducting tube in the bank, and this means that only one tube will be conducting in each bank at the end of a receiving period and these conducting tubes in the various banks will correspond to the symbols received. The conducting tubes will continue to conduct after the receiving period and serve as a means for storing the symbols.

As explained earlier, the burst of impulses representing the various symbols are sent out one after another in succession over a single wire, and, because of this, routing means must be provided in the receiving apparatus to distribute or allocate the bursts to the proper banks of transforming and storing tubes. The particular routing means shown herein includes a normally inoperative relay means for each bank of tubes, which relay means may be selectively rendered effective one after another to relay the bursts of impulses from a common impulse line to the various banks of transforming and symbol-storing tubes.

The relay means are rendered effective one after another by means of a routing control device consisting of a series of gaseous electron tubes which are connected in a chain to be fired and rendered conducting one after another in sequence in response to the marking impulses. The tubes of the routing control device are also connected so that the firing of any tube in the chain will cause any previously conducting tube of the chain to be extinguished and allow only one tube at a time to be conducting. The chain connections and extinguishing connections between the routing control tubes, therefore, enable the tubes to become conducting one at a time in sequence, and, as long as any tube is conducting, it renders its associated relay means operative to relay impulses from the common impulse line to its associated bank of transforming and symbol-storing tubes.

While the routing means is shown as consisting of a plurality of relays, it is obvious that the routing means could take other forms, such as a sequence switch which is capable of step-by-step operation to relay the impulses to the various banks.

The discriminating means in the receiving apparatus receives all the impulses which are sent from the sending apparatus and includes means which is responsive to both small and largeamplitude impulses and means which is only responsive to the large-amplitude impulses. The means which is responsive to all the received impulses passes these impulses to a common impulse conductor in the receiving apparatus, from which conductor the impulses are relayed selectively to the various banks of transforming and symbol-storing tubes. The means which is responsive to the large-amplitude impulses only, is effective to send an impulse to the routing control tubes to cause one of these tubes to be fired each time a large-amplitude impulse is received in the receiving apparatus.

The operation of the receiving apparatus is asfollows:

The receiving apparatus is prepared for the reception of data by causing the presetting tube or each bank of transforming and symbol-storing tubes and the first tube in the routing control device to be fired and rendered conducting.

The firing o! the presetting tube in each bank of transforming and symbol-storing tubes will, through mutual extinguishing connections, clear these banks of any previously stored symbols,

and the firing of the first tube in the routing control device will likewise cause any other tube of the device to be extinguished and insure that the first entry will always be routed to the first bank of transforming and symbol-storing tubes.

The conducting presetting tube of each bank will prepare the marking impulse tube in its bank 01' tubes to be responsive to signal impulses and will continue to be conductive until signal impulses are relayed to that bank and cause the marking impulse tube therein to be fired and rendered conducting.

The conducting routing control tube renders the relay means for the first bank effective and prepares the routing control tube for the second bank for firing in response to the first largeamplitude impulse to be received.

The receiving device is now ready to receive signals. As the first burst of impulses is received, the small and large-amplitude impulses will be passed on to the common impulse line and relayed from the common impulse line to the first bank of transforming and symbol-storing tubes, and these tubes will be operated one alter another in response to these impulses, the last tube to be operated being the symbol-representing tube corresponding to the symbol represented by the burst. The marking impulse, or largeamplitude impulse, which is the last impulse of the burst, will also be effective, through the discriminating means, to cause an impulse to be sent to the routing control tubes. The routing control tube for the second bank has been prepared for firing by the conduction in the first tube, and, when the impulse is sent to these tubes in response to the marking impulse of the burst, the second bank routing control tube is fired and rendered conducting.

The second bank routing control tube, when it is fired, causes the first bank routing control tube to be extinguished, and thereby the first bank relay means to return to its normal inoperative state; prepares the third bank routing control tube for operation in response to the next marking impulse; and renders the relay means for the second bank of transforming and sympol-storing tubes operative.

The next burst of impulses will cause the transforming and symbol-storing tubes of the second bank to be fired to set up and store the symbol represented by the second burst of impulses. As before, the last or marking impulse of this burst will cause the firing or the next routing control tube and prepare the next transforming and symbol-storing bank for reception of the next burst of impulses. In this way, the successive bursts of impulses are routed to the various banks of symbol-storing tubes and control the setting oi the various symbols therein.

After the sequence of bursts has been received, the conducting tubes representing the symbols in the various banks can be used to control an indicating means or a recording means or can be used to control the transfer of the symbols directly to other storing means for future use.

The invention is not limited to the use of five banks oi. transforming and symbol-storing tubes. as it is obvious that more banks could be used if it were desired to increase the capacity or the receiving apparatus.

Thus it is seen that applicants have provided a novel receiving apparatus for use in a systgln iorsending ass-resumes data at a rate of speed. Dn'rmnn Dlscm'rron The disclosed embodiment oi the invention is adapted to receive and store five symbols automatically in succession, which symbols are received in the form of bursts of impulses. Fig. 9 shows, in a general way, a train of impulses made up or the bursts of impulses which would be used to operate the receiving apparatus to store therein the symbols for A," Space," C," A, and HB A consideration of these bursts shows that the "Space symbol is represented by a burst containing one small-amplitude symbol-representing impulse followed by a large-amplitude marking impulse; the letter A" is represented by a burst containing two small-amplitude impulses and a. large-amplitude impulse; and the letter 3" is represented by three small-amplitude impulses and a large-amplitude impulse. In the instant embodiment, this relation between the various letters and the number of small-amplitude impulses extends to the letter Z, which would be represented by twenty-seven small-amplitude impulses i'ollowed by a large-amplitude marking impulse.

The tom of impulses as shown in this figure is one form which may be used, but the invention may be carried out with other forms 01 impulses just as long as a distinction is maintained between the variable number of impulses and the marking or controlling impulses. The numerals I. an, um," v!!! VII d t the order in which the symbols are transmitted and received, and similar numerals will be al plied to the various parts of the receiving apparatus which deal with these symbols.

It is not intended that the invention be limited to the use of the particular potentials and values or resistance and capacitance given in the following description, because the potentials applied to the various elements of the tubes are merely selected as convenient potentials for the disclosure, and the circuit elements of resistance and capacitance correspond in relative value to the potentials chosen. It is obvious that other potentials may be used and the values oi the circuit elements adjusted accordingly to maintain the proper relation between the various parts of the circuit. Throughout the drawings, the cathode heater elements are shown conventionally.

The bursts of positive potential impulses which are generated by means at a sending station during a transmitting operation, according to the symbols of the data being transmitted, are transmitted to the novel receiving apparatus and are impressed on a signal input terminal 330 (Fig. 8) of the receiving apparatus.

The details of the sending or impulse generating apparatus will not be given herein. For details of an impulse generating means which will generate the required number or small-amplitude impulses and a marking impulse in each burst to represent a symbol of data being transmitted, reference may be had to the United States Letters Patent No. 2,425,307, 0! which this application is a division.

With the values of resistance and capacitance given herein, the receiving apparatus will respond accurately to impulses which follow each other in a burst at about 50 kilocycles, with about a loo-microsecond spacing between bursts.

The receiving apparatus, shown in Figs. 1 to 8 inclusive, accepts the live bursts of impulses one after another and distributes them to different transforming and symbol-storing means. Each transforming and symbol-storing means consists of a group or bank of tubes, and the impulses are effective to selectively render one of the tubes of the group conducting, thereby to indicate and store the symbol which the number of impulses in the burst represents.

In order to set up a representation of the symbols which are received, the receiving apparatus contains discriminating means which receives all the transmitted impulses and is capable of distinguishing between the small-amplitude impulses and the large-amplitude impulses; a plurality of transforming and symbol-storing means consisting of groups or banks of symbol-representing and storing tubes which are operable to transform the bursts of impulses into representations of the symbols; and routing means which is operated each time a large-amplitude or marking impulse is received and is effective to route the successive bursts into different transforming and symbol-storing means.

Discriminating means The discriminating means is shown in Fig. 8. All of the supersonic signals which are impressed on the input terminal of the receiving apparatus are effective to control the discriminating means, which responds differently to the small-amplitude and the large-amplitude impulses.

Part of the discriminating means is responsive to both the small-amplitude and the large-amplitude impulses which are received and is capable of impressing a like number of impulses on a common impulse conductor in the receiving apparatus.

Another part of the discriminating means is responsive only to the large-amplitude or marking impulses and is effective to send an impulse to a routing control device to cause an operation thereof each time a marking impulse is received. This part of the discriminating means detects the large-amplitude marking impulse which indicates the end of a burst and causes the routing means to route the next burst to another symbol-storing group of tubes.

The part of the discriminating means which is responsive to all the received impulses consists of a pair of vacuum tubes 300 and 3M (Fig. 8), of which the tube 300 is affected by all the positive potential impulses which are received from the sending apparatus, and the tube 301 is controlled by the tube 300 and serves to change the phase of, and amplify, the potential impulses formed by the operation or the tube 300 and to impress the amplified impulses on a common impulse conductor in the receiving apparatus.

Tube 300 is normally non-conducting because of the bias on its control grid 302, but is rendered conducting each time a positive potential impulse is impressed on the control grid.

The potential supply circuit for the cathode 303 of the tube 300 starts at terminal 304, upon which is impressed a positive potential of 150 volts, and continues over conductor 30!, points 300 and 301, the variable resistor 303 of 10,000 ohms, resistor 303 of 5,000 ohms, point 3", and over the resistor 3 of 1,000 ohms and capacitor 312 of .1 microfarad in parallel to ground. The cathode 303 is connected to point M and may be given a positive potential of from 9 to 25 volts, depending upon the adjustment oi the resistor 300. The screen grid 3l3 also derives its potential from terminal 300 by means of a circuit which is the same as the circuit traced above to point 301 and then extends over conductor 3", resistor 3li of 10,000 ohms, points 3l3 and 3H, and over resistor 3|0 of 25,000 ohms to ground. The screen grid III is connected in this circuit at point 3 I 1 and is given a positive potential o! 43 volts. A circuit also extends from point 310, over conductor 3l3, point 320, and capacitor 32i oi? .1 microiarad to ground to absorb the shock of any abrupt application or change of potential in this circuit. The suppressor grid 322 is connected to ground over conductor 323.

The control arid 302 is connected to a circuit extending from the signal input terminal 330, over point 33L capacitor 332 of 250 micro-microfarads, resistor 333 of 10,000 ohms, point 330, and over conductor 323 to ground. A potential-tapping member 335 cooperates with the resistor 333 to enable the grid 302 to be connected to this circuit. Control grid 302 is normally at ground potential and prevents conduction in the tube 300 until the positive impulse is impressed on the signal input terminal 330 and raises the potential of the grid 302 to allow conduction to take place in the tube.

The anode 330 of the tube 300 has a normal positive potential of 150 volts applied thereto over a circuit extending from terminal 304, conductor 305, point 331, resistor 330 of 15,000 ohms, conductor 330, and point 340. As the tube 300 becomes conducting, the potential of the anode 330 will drop, due to the resistor 333, and this potential drop is impressed on the control grid 3 of the tube 30I to control the conduction in that tube.

The potential of the cathode 303 and the eflect of the input signal impulses on the control grid 302 can be regulated by the adjustable resistor 303 and the potential-tapping member 335, respectively, to enable the tube 300 to respond properly to both the small-amplitude and the large-amplitube positive impulses impressed on the signal input terminal 330.

The phase-changing and amplifying tube 301 has a zero bias and is, accordingly, normally conducting. The cathode 342 of this tube is connected directly to ground. A positive potential of volts is applied to the screen grid 303 of this tube by means of a circuit starting at terminal 3, upon which is impressed a positive potential of 105 volts, and continuing over conductor 30!. point 340, and conductor 3".

The circuit by which potential is supplied to the anode 333 starts at terminal 300 and extends over conductor 305, point 343, conductor 350, resistor 35! of 500 ohms, point 352, and resistor 303 of 5,000 ohms to the anode 340. Since the tube is normally conducting, its anode 343 will be at approximately 50 volts due to the resistors 35! and 353 in the anode circuit. However, this potential will rise toward volts as the conductivity in the tube is reduced by the control grid 3.

The control grid 30! is normally at ground potential, being connected to ground over point 300 and resistor 305 of 10,000 ohms. Point 300 in this circuit is electrostatically connected, through a capacitor 350 of 200 micro-microfarads, to the point 300 in the anode circuit for the tube 300, which connection enables the negative potential impulses caused by the conduction in tube 300 to be impressed on the control grid 3 to reduce conduction in tube 30!.

A potential-tapping member an co perates with the resistor "I in the anode potential supply circuit for the tube till and enables the positive potential rise in this circuit as conductivity is reduced in the tube to be impressed on the common impulse conductor (Fig. 6) in the receiving apparatus. The connection is from the current-tapping member I" to the terminal 858, which terminal is connected to the terminal I50 (Fig. 6), to which th common impulse conductor "0 is connected.

This part of the discriminating means, therefore, is operated in response to both the smallamplitude and the large-amplitude impulses and impresses an impulse on the common impulse conductor 300 each time a small-amplitude impulse or a large-amplitude impulse is received at the signal input terminal 830.

The other part of the discriminating means also contains two vacuum tubes, I and 301. and'is similar to the part described above. However, tube 060 is responsive to only the large-amplitude or marking impulses and controls the phasechanging and amplifying tube 381 to cause an impulse to be impressed on an impulse conductor for the routing control device each time a largeamplitude impulse is received.

Tube 308 is normally non-conducting but is rendered conducting each time a large-amplitude impulse is impressed on the input terminal.

The potential-supplying circuits for the anode 360. the screen grid I", and the suppressor grid I10 of tube 300 are similar to those given a ove for tube 300 and provide these elements with positive potentials of 150 volts and 43 volts and ground potential, respectively.

The cathode "I is supplied with positive potential from terminal 304 by a circuit extending over conductor I08, point 300, conductor "2, resistor 313 of 15,000 ohms, adjustable resistor l" of 10,000 ohms, resistor I" of 5,000 ohms, point I10. and over resistor ill of 5,000'ohms and capacitor 318 of .1 microfarad in parallel to ground. The cathode lll is connected to this circuit at point 318 and has a positive potential of between 21 and 30 volts impressed thereon, depending upon the adjustment of resistor 3'".

The control grid 31! is connected to a circuit extending from the signal input terminal 830, over point Ill, capacitor 300 of 250 micro-microiarads, resistor "I of 10,000 ohms, point "2, and conductor 303 to ground. Control grid 31! is connected to this circuit over resistor I" of 75,000 ohms and potential-tapping member 305 and is normally at ground potential.

The potential oi the cathode I'll and the efl'ect of the input signal impulses on the control grid 319 can be regulated by the adjustment of resistor Ill and the potential-tapping member 008, respectively, so as to prevent the small-amplitude impulses from aii'ecting the tube and allow only the large-amplitude impulses to cause conduction to occur in the tube 3".

Whenever tube 300 is rendered conducting, the potential oi its anode 800 will drop due to resistor 300 of 15.000 ohms in the anode potential supply circuit. A connection from point 381 in the anode potential supply circuit, over a capacitor 308 of 200 micro-microfarads to point 300, to which the control grid 390 of tube 361 is connected, enables the anode potential drop to control conduction in tube 301.

The phase-changing and amplifying tube 30'! of this part of the discriminating means also has a zero bias and is normally conducting. The

circuits for supplyin potential to the control grid 390, the cathode "I the anode 302. and the screen rid 39! are similar to those explained above for corresponding elements of tube 30L Since the tube 301 is normally conducting, its anode will normally have a potential of approximately 50 volts due to the resistors in the anode circuit. Each time a large-amplitude impulse is impressed on the receiving apparatus. tube 360 will become conducting and, through the connection between points 381 and 389, will impress a negative impulse on the grid 390, causing the grid 380 of tube 36'! to acquire a negative potential and reduce conduction in this tube. thereby causing the potential of the anode 392 to rise toward volts. A potential-tapping member 390 cooperates with resistor 390 of 5,000 ohms in the anode circuit and enables the potential rise in this circuit, as conduction in the tube is decreased, to be used as a positive potential impulse. Terminal 390, which is connected to the tapping member 39], is also connected to terminal 39'! (Fig. 7), to which is connected an impulse conductor for the routin control device upon which the positive potential impulses are impressed.

This part of the discriminating means. accordingly. can respond to the supersonic marking impulses and can send an impulse to control the routing means each time a marking impulse is received.

The discriminating means as a whole, therefore, enables the diflerent amplitudes of the input impulses to be utilized to provide different controls for the receiving apparatus.

Transforming and symbol-storing means In the disclosed embodiment, the receiving apparatus contains five banks of transforming and symbol-storing means; however, the number 01 banks may be increased or decreased if desired. The flve banks are shown in Figs. 1 to 5, inclusive, and are given the reference numerals I, II," III," IV," and V" to indicate the order in which they operate and the symbols which they will store. Since the circuits for the various banks are similar. the operation of all the banks will be clear from a description of one oi the banks.

Referring to Fig. l, which shows the bank for transforming the first burst of impulses into a single representation or a symbol and for storing this symbol, it is seen that a bank of transforming and symbol-storing means is made up of a plurality of gaseous electron tubes. The tubes are of the type having an internal potential drop of about 15 volts, when conducting, and having an anode, a cathode. and a. control grid which is given a negative bias with respect to the cathode and will prevent the tube from tiring until this bias is reduced to less than 15 volts negative with respect to the cathode. Of the plurality of gaseous electron tubes in the bank, there is a presetting tube "Preset,-which is fired before reception takes place, a marking impulse tube "Mark." as space symbol tube "Space," and a tube for each of the letters "A to Z" inclusive, although in this figure the tubes for the letters "B" to W inclusive have been omitted to simplify the show ing of the bank, as their circuits are identical with those for the other tubes and an understanding of the operation of the bank can be had from the circuits shown.

The presetting tube Preset in the bank is fired before reception begins in the receiving apparatus, and is used to clear the bank of any previously stored symbol and to insure that the sequential firing of the tubes in a bank, in response to the 11 impulses of a burst, will always begin with the same tube, which, in the instant embodiment, is the marking impulse tube Mark."

The marking impulse tube is not a symbol-representing tube but is included in the bank because a marking impulse is a part of every burst and the discriminating means impresses the marking impulse on the banks along with the diiierent numbers of small-amplitude impulses, and it is therefore necessary to include this tube in the bank so that the symbol-representing tubes will show the correct symbol at the end of a burst of impulses.

The tubes in the bank are connected for sequential firing in response to supersonic impulses, beginning with the presetting tube, then the marking impulse tube, and next the tubes for the space symbol Space and the letters A" to "Z," in that order. The marking impulse tube and the symbol-storing tubes are fired one after another in response to impulses relayed to a firing impulse conductor from the common impulse conductor 360. As each tube in the sequence is tired, it will be operable to extinguish any previousiy conducting tube of the bank, the last tube to be fired in any bank remaining conducting and serving to provide for the storage of a single representation of the symbol represented by the number of impulses in the burst.

The tubes which are conducting in the various banks at the end of a transmitting operation can be inspected to directly show the symbols stored in the various banks, can be used to control a remote indicating or recording apparatus, or can be used to directly transfer the symbols to other storing means.

The circuits for supplying the potentials and the operative connections between the tubes of a bank are as follows:

Negative potential is supplied to the cathodes of the tubes of this bank (Fig. i) by means of parallel circuits, one for each tube, extending to ground from a negative potential conductor 400. to which a negative potential of I50 volts is applied at terminal 40!. The circuit for the Y" tube is representative and extends from the supply conductor 400 at point 402, over resistor 403 of 150,000 ohms. point 404, resistor 405 of 100,000 ohms, points 400, 401, and 400 and to ground over resistor 409 of 15,000 ohms in parallel with resistor of 2,500 ohms and capacitor 4 of .001 microfarad in series. Cathode 4I2 of the "1! tube is connected to this circuit at point 401 and has a negative potential of approximately 8 volts when the tube is not conducting. When the tube is conducting, the cathode is also conductively coupled to its related anode by the discharge path through the tube, so that the positive potential which is applied to the anode will also be impressed on the cathode potential supply circuit and will cause the potential of the cathode M2 to rise from a negative potential of about 8 volts to a positive potential of about 50 volts.

The 2" tube, the last tube in the sequence, has a. cathode potential supply circuit which is equivalent to the other circuits. This circuit extends !rom point 4!! on the potential supply conductor 400. over resistor 4i0 oi 250,000 ohms, points 4" and 4", and to ground over resistor 4i! of 15,000 ohms in parallel with a resistor 420 of 2,500 ohms in series with a capacitor "I of .001 microi'arad. Cathode 422 of the "Z" tube is connected to this circuit at point 4".

The cathode potential supply circuits for all the tubes except the "Z tube are used to supply negative biasing potential for the control grids of the tubes next in the sequence, the connection being from the cathode circuit oi one tube to the control grid of the next tube in the sequence. These connections enable the sequential firing of the tubes by utilizing the potential rise of the cathode of one tube to prime the next tube to be operated, so that the next tube may be fired and rendered conducting when the next impulse is impressed on the firing impulse conductor 423. The grid of the Z tube, for instance, is connected over resistor 426 of 50,000 ohms, point 421, resistor 420 of 500,000 ohms, point 420, and conductor 430 to point 404 in the cathode potential supply circuit for the Y tube, from which point it derives a normal negative biasing potential 01 65 volts when the Y tube is not conducting. When the Y" tube becomes conducting and its cathode potential rises, it will cause the biasing potential of the grid of the Z tube to be reduced to almost its critical point, so that the "Z" tube can respond to the next firing impulse which is impressed on the bank. A capacitor "I of 250 micro-microiarads connects point 429 in the grid circuit with point 406 in the cathode circuit to speed up the application of the potential rise on the grid of the 2" tube when the "Y tube becomes conducting,

The presetting tube Preset," being the first tube in the series, does not have its control grid connected to a cathode potential supply circuit, but has a negative biasing potential of 64 volts supplied thereto by an equivalent circuit extending from point 432 on the conductor 400, over resistor 433 of 120,000 ohms, points 434 and 435, and resistor 436 of 90,000 ohms to ground, to which the control grid 431 is connected at point 435.

The grids of the tubes in the sequence from the marking impulse tube to the Z tube are electrostatically coupled to the firing impulse conductor by means of capacitors of i0 micromicroiarads, as capacitor 430, by which point 421 in the grid circuit of the 2" tube is connected to the firing impulse conductor 423. The firing impulse conductor 423 extends from the terminal 424, and this terminal is connected to terminal 425 (Fig. 6) of the relay means which relays the impulses from the common impulse conductor 350 to this bank. The normal negative bias of the grids of these tubes will normally render the firing impulses ineffective to cause the firing of the tubes; however, if any tube has been primed by the conduction in another tube in the sequence, the bias of the grid oi the primed tube will have been reduced sufliciently that the firing impulse can cause that tube to fire and become conducting.

The anodes of the tubes of this bank are connected to a common anode supply conductor 439, which is connected over resistor 440 of 2,000 ohms to terminal 4, which has a positive potential of 75 volts applied thereto.

When none of the tubes of the bank is conducting, the anodes will have a positive potential of 75 volts; however, when any tube in a bank is conducting, the potential of the anodes will be reduced to about 65 volts due to the drop across resistor 440.

At the moment one of the tubes of the bank is fired, its cathode will remain at a negative potential of about 8 volts while the capacitor, as 4 in its cathode circuit, is charging, and, due to the resistance in the anode potential supply circuit for this bank and the internal drop of the tube, the potential of the anode will drop to within about 15 volts of the cathode potential. This will cause a corresponding drop in the potential of the common anode potential supply conductor 438 for this bank, which drop is used to extinguish any previously conducting tube of the bank. The extinguishing action occurs because the potential of all the anodes of the tubes of the bank will drop as the potential 01' the anode potential supply conductor 4 drops. and this will cause the potential of the anode of a previously conducting tube to drop below the potential or its cathode, which has risen due to conduction in the tube, and will thus cause conduction to cease in the previously conducting tube and enable its control grid to regain control.

The presetting tube "Preset is fired by a circuit which may be closed by any convenient means prior to the reception of data. For simplicity in the diagram, the circuit is shown closeby a presetting key 442. The circuit starts at terminal 443, upon which a positive potential of I50 volts is impressed, and continues over con ductor 444, key 442, conductor 44!, resistor 446 oi 167,000 ohms, to point 484 in the circuit for the control grid 431. When this circuit is closed by the key 442, it applies positive potential to the grid and causes its potential to become more positive than the cathode, which causes the tube to fire and become conducting.

The operation of the bank is as follows:

The presetting tube "Preset" is fired by momentary closing of the presetting key 442 before reception of data takes place. The firing of this tube extinguishes any previously conducting tube in the bank and primes the marking impulse tube, so that the first impulse oi the burst which is relayed to the firing impulse conductor 42! of the bank will cause the marking impulse tube to be iixed and become conducting. The firing of the marking impulse tube will extinguish the preset tube, and conduction in the marking impulse tube will prime the space symbol tube Space." The succeeding impulses of the burst will fire the tubes "Space," "A," B, C," and so on, depending upon the number oi impulses in the burst. After the last impulse in the burst has fired a tube, that tube will remain conducting and will thereby store the symbol and provide a visual indication of the symbol which was represented by the burst. The potential 01' the cathode of this conducting tube will be positive, and this will be the only tube in the bank having its cathode at a positive potential. Conductors, as 450, extending from the cathodes of the symbol-representing tubes, can be sensed by any suitable means for this condition and can control a remote indicating or recording mechanism or can be used to control the direct transfer of the setting of the bank to another storage means.

The other banks for transforming and storing the second, third. fourth, and fifth symbols operate exactly as this bank. These banks are prepared by the presetting keys 45i, 452. 453. and 454 (Figs. 2, 3, 4, and 5), which cause the presetting tubes to be fired. The circuits for firing the presetting tubes are shown closed by individual keys for simplicity in the showing of the circuits, but it is obvious that all these circuits could be closed by contacts of a single presetting relay or by some other similar construction.

The anodes of the tubes of each bank are connected together, and over a resistor to a separate source oi potential, so that the mutual extinguish- 14 ing action between the tubes is limited to the tubes of a bank. At the end of a receiving operation, therefore, the last tube to operate in each bank will remain conducting until the banks are preset for another receiving operation.

The firing conductors 455, 458, 451, and 458 for the II," III, IV," and "V" banks (Figs. 2, 3, 4, and 5) are connected to terminals 459, 400, 46 l, and 482. which terminals are connected to terminals 463, 464, 485, and 466, respectively (Fig. 6), of the relay means for the various banks.

As the relay means for the various banks become operative one after another to relay impulses to the firing conductors, the tubes in the various banks will be fired in sequence, and, at the end 01' the receiving operation, the bursts of impulses will have been transformed into single representations of the symbols and those tubes in the several banks will be conducting which correspond to the symbols which have been transmitted to the receiving apparatus.

Routing means Routing means, comprising relay means and a routing control device, are provided in the receiving apparatus to route the successive bursts of impulses into the different banks of transforming and symbol-storing means.

A plurality of relay means, one for each bank of transforming and symbol-storing means, are used to selectively relay the impulses from the common conductor 360 (Fig. 6) to the firing impulse conductors of different banks of transforming and symbol-storing means. The several relay means are normally unresponsive to the impulses on the common impulse conductor 380 but can be successively "primed" or made responsive under control of the routing control device so that difierent relay means will be responsive to the successive bursts oi impulses and can cause the successive bursts of impulses to control the setting of the symbols in the various banks.

The rputing control device (Fig. 7) includes a 7 control tube for each relay means, and these control tubes, which are gaseous electron tubes of the same type as those used in the transforming and symbol-storing means, are connected for sequential step-by-step operation each time a marking impulse is received. As each control tube is fired and becomes conducting, it extingulshes any previously conducting control tube of the device; primes its related relay means to render it effective to relay impulses from the impulse conductor 360; and primes the next control tube in the sequence so that it will fire and become conducting when the next marking impulse is received.

Inasmuch as the marking impulses follow the small-amplitude impulses in a burst, it is necessary to tire the control tube for the first bank before the first burst is received. The tiring of the first control tube will extinguish any previously conducting control tube which might have remained conducting from a previous operation of the device, and insures that the first burst of impulses will be entered in the first bank of transforming and symbol-storing means.

The routing control device is shown in Fig. 7, in which the control tubes are given the reference numerals I," II," "III," IV," and "V" to indicate with which of thebursts they are operative. As the circuits for the various control tubes of the routing control device are similar, it is believed that the operation or the device will be 15 clear from a description of representative circults.

Potential is supplied to cathode 410 of the "I" control tube by a circuit which has two branches, one of which is also utilized to supply a negative biasing potential for the relay means related to the "I" control tube, and the other of which is also utilized to supply negative biasing potential to the control grid 4' for the 11 control tube. The one branch extends from a negative potential supply conductor 412, to which a negative potential or 150 volts is applied at terminal 4", and continues over point 414, resistor 415 of 390,000 ohms, point 415, resistor 4'" of 150,000 ohms, to points 410, 419, and 440. The other branch extends from the potential supply conductor 412 at point 482 and continues over resistor 483 of 300,000 ohms, point 404, and resistor 485 of 200,000 ohms to the points 419 and 400. From the points 410 and 480, the two branches continue to ground over resistor 406 of 15,000 ohms in parallel with resistor 401 of 2,500 ohms and capacitor 488 oi .002 microiarad in series. The cathode 410 is connected at point 410 in this circuit and is given a negative potential of approximately 9 volts whenever the tube is not conducting. When the tube is conducting, the electron discharge enables a positive potential applied to the anode to be applied to the cathode and will cause the potential of the cathode to rise to a positive potential of about 50 volts.

A circuit extends from point 416 in said one branch and continues over conductor 409, point 490, conductor 4!, and terminal 492, which is connected to terminal 408 (Fig. 6) and supplies a negative biasing potential 01' about 50' volts to the relay means for the first bank of transiorming and symbol-storing means. This circuit also enables the potential rise of the cathode 410, due to conduction in the control tube. to be used to reduce the negative bias or prime" the relay means.

A capacitor 494 of 50 micro-microtarads is connected between points 410 and 490 to cause the change in potential to be applied rapidly when the relay means is primed by the potential rise of the cathode.

A circuit extends from said other branch of the cathode potential supply circuit at point 404 and continues over resistor 495 of 500,000 ohms, point 498, and resistor 491 of 50,000 ohms to grid 4' of the I! control tube to supply this grid with a normal negative potential of about 05 volts. This circuit enables the II tube to be primed by having this negative potential reduced to 30 volts by the potential rise 01' cathode 410 when the "1" tube is conducting.

Grid 4' of the II tube is connected over point 408 and capacitor 5M of micro-microtarads to an impulse conductor 542, which is connected to terminal 391, upon which is impressed a positive impulse by the discriminating means each time a marking impulse is received. These positivelmpulses will not be able to tire any of the tubes unless the tube which is to be fired has been primed.

The "1" tube is the first tube in the sequence. and its grid 503 can not derive its negative bias from the cathode potential supply circuit of a preceding tube. A circuit extending from point 504 on conductor 412, and over resistor 505 of 150,000 ohms, point 506, and resistor 501 or 100,- 000 ohms to ground, supplies grid Sill with a negative biasing potential or 60 volts over point 500 and resistor 50! of 500,000 ohms.

Since the routing control tubes are fired in response to marking impulses which occur after the small-amplitude impulses or the bursts, the I routing control tube must be fired from a different source before the first burst is received, in order that the relay means for the first transforming and symbol-storing bank can be primed and will respond to all the impulses of the first burst. This may be accomplished in any convenient manner; for instance, a presetting key (Fig. '1) can momentarily close a circuit starting from terminal ill], upon which a positive potential of 150 volts is impressed, and continuing over the'key 509. resistor 5H of 167,000 ohms to point 546 in the circuit of rid 50!. The application of this positive potential to the grid 543 will reduce the negative bias of the grid and cause the tube to fire and become conducting, thereby rendering the relay means for the first bank of transforming and symbol-storing means operative and preparing the 11" routing control tube for firing in response to the marking impulse of the first burst. The circuit closed by key 508 may be closed momentarily by a presetting relay along with the presetting circuits of the transforming and symbol-storing banks, as explained earlier herein.

Potential is applied to the anode iii of the I" tube by means of a circuit starting at terminal SIB, upon which is impressed a positive potential of 75 volts, and extending over resistor 5" of 250 ohms, point ill, resistor MS of 2,000 ohms, and conductor 520, to which anode Si! is connected. The anodes of the other tubes are also connected to conductor 520, and, when none of the tubes is conducting, the potential of the anodes will be '75 volts, but, when any tube is conducting, this potential is reduced to 65 volts due to the resistors 5H and SIS. Point M8 in this circuit is connected to ground over a capacitor of 8 microfarads to absorb the shock of an abrupt application or change in potential in this circuit. The common resistance in the anode potential supply circuit enables the firing 01' any tube of the routing control device to extinguish conduction in any previously conducting tube in the device in the manner explained earlier herein.

From the above description, it is clear that the control tubes in the routing control device will be fired one after another as the successive bursts are received, and will prime the relay means for the several banks one after another in succession.

The relay means are shown in Fig. 6 and consist of a pair of vacuum tubes for each transforming and symbol-storing bank, which relay means have been given the reference numerals ran, um," and v t i di t which bank of transforming and symbol-storing tubes they are related and also to indicate the order in which they operate. A description of the relay means shown at "I in Fig. 6 will be given, and, as the relay means for the other banks are similar. it is believed that an understanding of these means and their operation will be clear from this description.

Tubes I25 and 526, which constitute the means for relaying impulses from the common impulse conductor I to the first bank of transforming and symbol-storing tubes, are normally inoperative to relay the positive impulses from the common impulse conductor 360, because the control grid 521 of tube 525 is normally given a negative bias which the positive impulses cannot overcome. The tube 525 is "primed by having the negative bias oiits grid Ill reduced, and in this condition the tube can respond'to the positive potential impulses on the common impulse conductor "land can cause the impulses to be relayed to the firing impulse conductor 42! for the tlrlsisbank or transforming and symbol-storing tu The cathode III or tube 820 is connected to ground over point I20. The anode I30 of tube 525 is given a positive potential oi 150 volts over a circuit starting at terminal III, upon which is impressed a positive potential of 150 volts, and continuing over potential supply conductor I01, point 033, resistor I34 or 000 ohms. point 005, resistor 030 or 5,000 ohms, and point III to the anode I30. The screen grid 030 is given a normal positive potential of 150 volts by being connected to point I" in the above anode circuit.

The control grid 021 is connected over point 000 and resistor 040 or 10,000 ohms to terminal 400, which, as explained before, is given a negative biasing potential of about 50 volts from one branch or the cathode potential supply circuit for the "I" routing control tube (Fig. 7). The control grid I2! is also connected electrostatically to the common impulse conductor 300 (Fig. 6) from point 530 over a capacitor "I of 100 micromicrofarads. The potential on the grid 82'! is normally sufilciently negative that the tube 520 is not responsive to the positive potential impulses on the impulse conductor 300, but, when the I" control tube of the routing control device is conducting. the potential rise of its cathode 410 will reduce the negative potential of grid 52'], or prime the tube III so that it will be capable of responding to the impulses on conductor 380 and become conducting each time an impulse occurs on that conductor. Whenever tube 525 becomes conducting, the potential of its anode 530 will drop due to the resistors 534 and 030 in its anode potential supply circuit, and, through an electrostatic connection from point it! over capacitor 542 of 100 micromicrofarads and point 056, this drop is applied as a negative potential impulse on the control grid of the phase-changing and amplifying tube 526.

Tube 520 is a zero-biased tube and is normally conducting. This tube has its cathode 544 directly connected to ground; its screen grid 545 connected over resistor I40 01 500 ohms, point 041, and conductor 048 to terminal 540, to which is applied a positive potential of 105 volts: and its control grid 005 connected to ground from point 558 over resistor I51 01 10,000 ohms, and also electrostaticaliy connected to the anode 530 of tube 525, as explained above.

The anode 550 of the phase-changing and amplifying tube 020 is connected over resistor 050 of 5,000 ohms to point 500 on the potential supply conductor "2, which is connected to terminal "I, to which is applied a positive potential of 150 volts. As this tube is normally conducting, anode 050 will normally have a potential oi 50 volts, but, whenever a negative potential impulse is impressed on the control grid "0, conduction in the tube will be reduced and the potential of the anode will rise. A potential-tapping member "I cooperates with resistor 059 to enable this a rise to be utilizedas a positive potential impulse which is impressed on the firing impulse conductor 428 (Fig. 1) of the first bank of transforming and symbol-storing means to cause the iiring oi the tubes in that bank. The connection 18 {rem thepotential-tapping "I to the conductor extends from the potential-tapping member "I over conductor I42 to terminal III, which, as explained above, is connected "to terminal 424 (Fig. 1), to which the firing impulse conductor 420 is connected.

The other relay means will. when efiective, relay impulses from the common impulse conductor 880 to the thing impulse conductors of their respective banks.

Terminals 000, 504, 500, and 000 (Fig. 7), which are connected to terminals 001, 060, I00, and I10, respectively (Fig. 6), supply biasing potential to the various relay means and enable the 11" III," "IV," and "V control tubes or the routing control device to prime the relay means one after another.

As explained earlier herein, terminal 403 (Fig. 6) is connected to terminal 400 (Fig. 2), to which the firing impulse conductor 405 for the second bani: is connected. and enables the relay means to impress as many firing impulses on this conductor as there are impulses in the second symbol-representing burst of impulses impressui on conductor 800.

Similarly, terminals 464, 405, and 400 (Fig. 6) are connected to terminals 480, "I, and 482 of Figs. 3, 4, and 5, respectively. to enable the third. fourth, and fifth bursts oi impulses to be relayed to the firing conductors 408, 451, and 450 of their respective banks oi transforming and symbolstoring means.

An alternate form oi routing means employing a conventional step by step sequence switch and a conventional operating circuit therefor is shown in Fig. 10.

The switch is of the type in which a rotatable wiper I400 operates step by step to engage cooperating contacts, one after another, the wiper being given a step of movement through a pawl and ratchet drive each time a switch-operating magnet I40I changes from its energized to its deenergized condition.

The wiper I400 is connected to a terminal I402 which is connected to terminal 350 (Fig. 8). As explained earlier herein a positive impulse will occur at terminal 850 each time a signal impulse of either kind is received.

As shown in Fig. 10, the wiper is in the position which it occupies during the reception of the first burst of signals. Impulses on terminal 358 will be transmitted over the wiper to contact I 403 which is connected over terminal I 404 to terminal 424 (Fig. 1) to cause the first bank of transi'orming and symbol-storing tubes to be operated. The last or large amplitude impulse of the first burst will cause the switch operating magnet I I to be energized momentarily and to be deenergized to allow the wiper to move into engagement with 7 contact i405 which is connected over terminal I406 to terminal 450 (Fig. 2) to enable the second burst of impulses on terminal 368 to be transmitted to the second bank of transforming and symbol-storing tubes to cause their operation. As before, the last impulse of the burst will cause the switch operating magnet III to be energized momentarily and to be deenergized to allow the wiper to move into engagement with the contact I401 which is connected over terminal I400 to terminal 480 (Fig. 3) of the next bank of transforming and symbol-storing tubes so that the third burst of impulses can be transmitted to the third bank of transforming and symbol-storing tubes to cause their operation. In a similar manner the wiper will engage further contacts I40. and illll which are connected over terminals MII and i2 respectively to terminals (Fig. 4) and 82 (Fig. 5) to transmit the impulses of the fourth and fifth bursts of impulses to their respective banks of transforming and symbolstoring tubes.

Since only five banks of transforming and symbol-storing tubes have been provided, the switch wil move to contact l3 after the fifth burst has been received. Contact I3 is connected to contact llllfl so that the switch is again in position to cause a first burst of impulses to be routed to the first bank of transforming and symbol-storing tubes. In a similar manner further step by step operation of the wiper will cause the following bursts to be routed into the proper banks of transforming and symbol-storing tubes.

The operating magnet Hill is included in the anode circuit of a thyraton Hi5 along with an interrupter switch Hi6 which is opened by the armature ill! of the operating magnet Hill as the armature pivots about its pivot point Hi8 and nears its full extent of operation when the magnet is energized.

The grid of the thyraton "I5 is given a negative bias from a resistor network extending between a suitable source of negative potential and ground. The grid is also coupled over capacitor Hi9 and terminal to terminal 396 (Fig. 8) which, as has been explained earlier, has a positive impulse impressed thereon each time a large amplitude signal is received The bias on the grid is such that it will prevent the thyraton from conducting until the positive impulse on terminal 396 is impressed on the grid over capacitor llli'l.

The cathode of the thyratron is grounded.

When the thyratron is rendered conducting, it will continue to conduct until the armature ll" of the switch operating the magnet Hill opens the interrupter switch Hi6.

Each impulse on terminal 396 (Fig. 8) when the last impulse of a burst is received will cause thyratron l5 to become conducting and energize operating magnet lllll. As the magnet becomes energized it shifts its armature lll'l which opens the anode circuit of the thyratron Hi5 at switch Hi6, extinguishing the thyratron and deenergizingthe magnet. Deenergization of the magnet allows spring ii to return the armature llll to its unoperated position and causes the pawl to move the wiper 00 to the next contact.

With this form of routing means, the wiper will be shifted between bursts to direct the impulses of the bursts to the proper banks of transforming and symbol-storing tubes, the shifting being controlled by the last or marking impulse in each burst.

Thus, by the operation of the routing means, the successive bursts of impulses which are received are automatically sent to the proper banks of transforming and symbol-storing means, where the bursts are transformed into single representations of the various symbols and are stored.

OPERATION In the operation of applicants novel receiving apparatus, the apparatus is preset or prepared for the reception of data by firing, in any convenient manner, a presetting tube in each of the plurality of banks of transforming and symbol-storing tubes and by firing the first control tube of the routing control device. This presetting operation clears the receiving apparatus of any symbols which remained therein from a previous operation, and conditions the routin control device to prime the relay means for the first bank of transforming and symbol-storing tubes so that the first burst of impulses will be routed to that bank.

As the bursts of impulses are received by the receiving apparatus. the discriminating means passes them to the relay means for the various banks of transforming and symbol-storing tubes. The discriminating means also distinguishes between the small and large-amplitude impulses of a burst and causes the routing control device to operate and prime the relay means for the next bank when the large-amplitude impulse is received, so that the next burst of impulses will be routed to the next bank of transforming and symbol-storing tubes. In this manner, the relay means are primed one after another as the bursts are received, and cause the various bursts to be relayed to the proper banks of transforming and symbol-storing tubes.

The impulses relayed to the various banks of transforming and symbol-storing tubes will cause the step-by-step operation of the tubes of the banks to transform the different numbers of impulses in the bursts into single representations of the symbols, so that, at the end of the receiving operation, those tubes which have been fired and remain conducting in the various banks will correspond to the keys which were set in the sending apparatus and will provide an indication of the symbols making up the data which has been transmitted and received, which symbols are stored until the receiving apparatus is preset for another receiving operation.

Applicants novel receiving apparatus, therefore, receives data which has been transformed into bursts of different numbers of discrete supersonic signals and has been transmitted thereto. and transforms the supersonic signals back into direct representations of the data and enables the data to be stored.

While the form of the invention herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form or embodiment herein disclosed, for it is susceptible of embodiment in various forms all coming within the scope of the claims which follow.

What is claimed is:

1. In a receiving apparatus for a communication system in which different numbers of electrical impulses are assigned to represent different symbols which may be transmitted, the last of the impulses representing a symbol being distinctive from the rest, the combination of a plurality of banks of electron devices, the devices in the banks being differentially operable to count the number of impulses in a corresponding plurality of bursts and transform the impulses into direct representations of symbols in response to different number of impulses which represent the symbols and to store the representation of the symbols; common means upon which bursts of impulses are impressed in succession, each burst containing the number of impulses corresponding to that assigned to the symbol which it represents; normally inoperable relay means related to each of said plurality of banks for selectively routing the impulses from the common means to its related bank to render the devices in the bank responsive to one of the bursts of impulses; and means controlled by the last and distinctive electrical impulse in each burst to render the several relay means operative one after another as the bursts are received. to thereby enable the various bursts of impulses to cause the differential operation 01' the devices in the plurality of banks of devices to set up direct representations of the symbols represented by the different numbers of impulses in the bursts.

2. In a receiving apparatus for a communication system in which different numbers of signal impulses are assigned to represent diflerent symbols which may be trasmitted and in which a symbol is transmitted as a burst oi impulses containing a number oi small-amplitude impulses which are followed by a large-amplitude terminal impulse, the combination of a plurality of banks 01 transforming and storing means, each bank including a plurality of electron devices al which diiierent numbers of devices are operable in response to diflerent numbers of impulses in the bursts to transform the bursts oi impulses into direct representations of the slimbols represented by the bursts; means to connect the devices of a bank for sequential operation one after another in response to impressed impulses; an impulse conductor for each bank by which impulses are impressed on the devices of the bank; input means upon which the bursts of signal impulses are impressed one after another in succession; routing means for selectively routing the impulses from the input means to the impulses conductors ior the plurality of banks of transforming and storing means; and means controlled by the last or large-amplitude impulse in each burst to cause the routing means to route the next burst to the impulse conductor for another one of the plurality of banks of transforming and storing means, whereby the successive bursts of signal impulses will be routed to control the operation of the banks of transforming and storing means one after another in succession.

3. In a receiving apparatus for a communication system in which diil'erent numbers 01' electrical impulses are assigned to represent different symbols which may be transmitted, the last of the impulses representing a symbol being distinctive from the rest. the combination of a plurality of banks and gaseous electron tubes; means connecting the tubes in each bank for step-by-step operation in sequence in response to the electrical impulses, the different numbers of electrical impulses forming bursts and causin different numbers of tubes to be operated to transform the bursts into direct representations of the symbols; means common to all the banks of tubes and upon which the bursts of electrical impulses are impressed in succession. each burst containing a number of electrical impulses corresponding to that assigned to the symbol which it represents; a thermionic valve related to each of said plurality of banks of tubes for selectively relaying electrical impulses from the common means to its related bank of tubes to cause a number of tubes therein to be operated according to one of the bursts of signals; means normally giving the thermionic valves a suificient bias so that they will not respond to the electrical impulses; and means operable by the distinctive electrical impulses oi the several bursts to reduce the bias on the thermionic valves one after another in sequence to enable the valve to successively respond to the electrical impulses and relay the successive bursts to the several banks of tubes in succession.

4. In a receiving apparatus for a communication system in which different numbers oi electrical impulses are assigned to represent difl'erent symbols which may be transmitted, the last of the impulses representing a symbol being distinctive irom the rest. the combination of a plurality of banks of gaseous electron tubes; means connecting the tubes in each bank for step-bystep operation in sequence in response to the electrical impulses, the diil'erent numbers of electrical impulses forming bursts and causing difrerent numbers of tubes to be operated to transform the impulses into direct representations of the symbols; means common to all the banks of tubes and upon which the bursts oi electrical impulses are impressed in succession, each burst containing the number of electrical impulses corresponding to that assigned to the symbol which is represents; a thermionic valve related to each of said plurality oi banks for selectively relaying electrical impulses from the common means to its related bank of tubes to cause a number of tubes therein to be operated according to one of the bursts of impulses; means normally giving the thermionic valves a sufilcient bias so that they will not respond to the electrical impulses; and electron devices operable one at a time in sequence in response to the distinctive electrical impulse in each burst for reducing the bias on the thermionic valves one after another to enable the valves to respond to the electrical impulses and route the successive bursts into different banks of tubes.

5. In a receiving apparatus for a communication system in which diilerent symbols which may be transmitted arerepresented by bursts oi electrical impulses, the burst containing diilerent numbers of impulses according to the symbols and the last impulse in each burst being distinctive irom the others in a burst, the combination of a plurality of banks of gaseous electron tubes: means connecting the tubes in each bank for operation one at a time in step-by-step sequence in response to the electrical impulses, the different numbers 01 impulses in the bursts being effective to cause difl'erent numbers of tubes to be operated in the banks and enable the last tube to be operated in each bank to provide a direct representation of the symbols; common means upon which the bursts of electrical impulses are impressed in succession; a relay device related to each of said plurality of banks for selectively relaying the electrical impulses irom the common means to its related bank oi tubes to cause a number of tubes therein to be operated according to the number of impulses in one of the bursts; a gaseous electron routing control tube for each relay device; means connecting the routing control tubes for operation one at a time in sequence. the connections enabling conduction in one tube to prime the next tube in the sequence to be operated in response to routing control impulses; means controlled by the last electrical impulse in each burst to send a routing control impulse to the routing control tubes to cause the primed tube to operate; and means enabling routing control tubes to render their related relay devices operable when the control tubes are operating, thereby to enable the relay devices to relay the electrical impulses in the various bursts to the proper banks of tubes. 

